Brain Natriuretic Peptide Gene Research Articles

Temporal relation of cardiac hypertrophy, oxidative stress, and fatty acid metabolism in spontaneously hypertensive rat

Left ventricular hypertrophy is an adaptive response to hypertension, and an independent clinical risk factor for cardiac failure, sudden death, and myocardial infarction. As regression of cardiac hypertrophy is associated with a lower likelihood of cardiovascular events, it is recognized as a target of antihypertensive therapy. This necessitates identification of factors associated with the initiation and progression of hypertrophy. Oxidative stress and metabolic shift are intimately linked with myocardial hypertrophy, but their interrelationship is not clearly understood. This study proposes to identify the temporal sequence of events so as to distinguish whether oxidative stress and metabolic shift are a cause or consequence of hypertrophy. Spontaneously hypertensive rat (SHR) was used as the experimental model. Cardiac hypertrophy was apparent at 2 months of age, as assessed by hypertrophy index and brain natriuretic peptide gene expression. Enhanced myocardial lipid peroxidation accompanied by nuclear factor-kappa B gene expression in one-month-old SHR suggests that oxidative stress precedes the development of hypertrophy. Metabolic shift identified by reduction in the expression of peroxisome proliferator-activated receptor-alpha, medium chain acyl CoA dehydrogenase, and carnitine palmitoyltransferase 1β was seen at 4 months of age, implying that reduction of fatty acid oxidation is a consequence of hypertrophy. Information on the temporal sequence of events associated with hypertrophy will help in the prevention and reversal of cardiac remodeling. Investigations aimed at prevention of hypertrophy should address reduction of oxidative stress. Both, oxidative stress and metabolic modulation have to be considered for studies that focus on the regression of hypertrophy.

RE1-silencing transcription factor (REST) and REST-interacting LIM domain protein (RILP) affect P19CL6 differentiation

During cardiac development, the heart produces the atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). These peptides are found in high levels in cardiomyocytes and, like a number of other embryonic genes, are up-regulated in both failing and hypertrophied ventricles. At the transcriptional level, BNP and ANP genes are regulated through RE1 regulatory element, which binds RE1-silencing transcription factor (REST). REST/NRSF-interacting LIM domain protein (RILP) is required for the nuclear targeting and function of REST. In this study, the role of RILP and REST in cardiomyocyte development using a model system was studied by analyzing the expression of RILP and REST as well as several cardiac-specific genes during P19CL6 cell differentiation. Effects of RILP overexpression and transcriptional regulation of RILP in differentiating P19CL6 cells were also studied. RILP expression is transiently reduced during P19CL6 cell differentiation; however, REST expression remains unchanged. This transient reduction in RILP expression correlates with de-repression of sarcomeric myosin heavy chain, a marker for cardiomyocyte differentiation. Reporter gene analysis shows that RILP gene is down-regulated through 5'-regulatory elements before cardiac-specific gene expression. These results suggest that RILP expression and function control REST action more so than does REST expression and is an important regulatory role in cardiomyocyte differentiation.

Myocardin-Related Transcription Factor A Is a Common Mediator of Mechanical Stress- and Neurohumoral Stimulation-Induced Cardiac Hypertrophic Signaling Leading to Activation of Brain Natriuretic Peptide Gene Expression

Subjecting cardiomyocytes to mechanical stress or neurohumoral stimulation causes cardiac hypertrophy characterized in part by reactivation of the fetal cardiac gene program. Here we demonstrate a new common mechanism by which these stimuli are transduced to a signal activating the hypertrophic gene program. Mechanically stretching cardiomyocytes induced nuclear accumulation of myocardin-related transcription factor A (MRTF-A), a coactivator of serum response factor (SRF), in a Rho- and actin dynamics-dependent manner. Expression of brain natriuretic peptide (BNP) and other SRF-dependent fetal cardiac genes in response to acute mechanical stress was blunted in mice lacking MRTF-A. Hypertrophic responses to chronic pressure overload were also significantly attenuated in mice lacking MRTF-A. Mutation of a newly identified, conserved and functional SRF-binding site within the BNP promoter, or knockdown of MRTF-A, reduced the responsiveness of the BNP promoter to mechanical stretch. Nuclear translocation of MRTF-A was also involved in endothelin-1- and angiotensin-II-induced activation of the BNP promoter. Moreover, mice lacking MRTF-A showed significantly weaker hypertrophic responses to chronic angiotensin II infusion than wild-type mice. Collectively, these findings point to nuclear translocation of MRTF-A as a novel signaling mechanism mediating both mechanical stretch- and neurohumoral stimulation-induced BNP gene expression and hypertrophic responses in cardiac myocytes.

Metoprolol Treatment Lowers Thrombospondin‐4 Expression in Rats with Myocardial Infarction and Left Ventricular Hypertrophy

Thrombospondins are matrix proteins linked to extracellular matrix remodelling but their precise role in the heart is not known. In this study, we characterised left ventricular thrombospondin-1 and -4 expression in rats treated with a beta-blocker metoprolol during the remodelling process in response to pressure overload and acute myocardial infarction. Left ventricular thrombospondin-1 and thrombospondin-4 mRNA levels increased 8.4-fold (p < 0.001) and 7.3-fold (p < 0.001) post-infarction, respectively. Metoprolol infusion by osmotic minipumps (1.5 mg/kg/hr) for 2 weeks after myocardial infarction decreased thrombospondin-1 and thrombospondin-4 mRNA levels (55% and 50%, respectively), improved left ventricular function, and attenuated left ventricular remodelling with reduction of left ventricular atrial natriuretic peptide and brain natriuretic peptide gene expression. Thrombospondin-1 and -4 mRNA levels correlated positively with echocardiographic parameters of left ventricular remodelling as well as with atrial natriuretic peptide and brain natriuretic peptide gene expression. Moreover, there was a negative correlation between left ventricular ejection fraction and thrombospondin-1 mRNA levels. In 12-month-old spontaneously hypertensive rats with left ventricular hypertrophy, metoprolol decreased left ventricular thrombospondin-4 levels and attenuated remodelling while thrombospondin-1, atrial natriuretic peptide and brain natriuretic peptide mRNA levels as well as left ventricular function remained unchanged. In metoprolol-treated spontaneously hypertensive rats, thrombospondin-4 gene expression correlated with parameters of left ventricular remodelling, while no correlations between thrombospondins and natriuretic peptides were observed. These results indicate that thrombospondin-1 expression is linked exclusively to left ventricular remodelling process post-infarction while thrombospondin-4 associates with myocardial remodelling both after myocardial infarction and in hypertensive heart disease suggesting that thrombospondins may have unique roles in extracellular matrix remodelling process.

The effects of intra-cage aspen tube on cardiac morphology and gene expression

According to the European recommendations rodents should be provided with a nest box if there is insufficient nesting material to build a complete, covered nest. Rats are generally poor nest builders; hence an additional structure is needed. Optimally, housing refinement may be combined with better science; at least it should not detract from the scientific integrity. In order to evaluate these options, there is a need to assess the items used in individual research projects. Studies investigating molecular mechanisms of cardiac hypertrophy and heart failure are typically long-lasting studies; therefore, refinement of the housing of rats in these studies is important. The aim of this study was to evaluate in rats whether a wooden tube has any impact on cardiac morphology or on basal gene expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP); known markers of cardiac overload, hypertrophy and heart failure. The experimental protocol simulated cardiovascular studies, but without any surgical operations. A total of 42 male Hsd:SD rats were used in an eight-week experiment. After weaning, the experimental group was provided with a rectangular aspen tube and nesting material, and the control group with only nesting material. ANP and BNP gene expression were measured from the left ventricles with Northern blot analysis postmortem along with the absolute weights of the whole heart, left and right atria and left and right chambers. The weights of the whole heart and left chamber were also analysed in relation to body weight. No statistically significant differences were observed in any of these variables. The inter-individual variation was also unchanged by the cage item. In conclusion, the aspen tube does not disrupt research results or alter the number of animals needed and can therefore be recommended for enrichment purposes in cardiovascular studies.

Gene Expression of ANP, BNP and ET-1 in the Heart of Rats during Pulmonary Embolism

AimsAtrial natriuretic petide (ANP), brain natriuretic peptide (BNP) and endothelin-1 (ET-1) may reflect the severity of right ventricular dysfunction (RVD) in patients with pulmonary embolism (PE). The exact nature and source of BNP, ANP and ET-1 expression and secretion following PE has not previously been studied.Methods and ResultsPolystyrene microparticles were injected to induce PE in rats. Gene expression of BNP, ANP and ET-1 were determined in the 4 cardiac chambers by quantitative real time polymerase chain reaction (QPCR). Plasma levels of ANP, BNP, ET-1 and cardiac troponin I (TNI) were measured in plasma. PE dose-dependently increased gene expression of ANP and BNP in the right ventricle (RV) and increased gene expression of ANP in the right atrium (RA). In contrast PE dose-dependently decreased BNP gene expression in both the left ventricle (LV) and the left atrium (LA). Plasma levels of BNP, TNI and ET-1 levels dose-dependently increased with the degree of PE.ConclusionWe found a close correlation between PE degree and gene-expression of ANP, and BNP in the cardiac chambers with a selective increase in the right chambers of the heart.The present data supports the idea of natriuretic peptides as valuable biomarkers of RVD in PE.

Ischemia‐Reperfusion Induces Transcriptional Activation of Brain Natriuretic Peptide Gene via ERK1/2 in H9c2 cells.

Brain natriuretic peptide (BNP) is a cardiac hormone released from heart ventricular cells in response to myocyte stretch. Although BNP has recently been shown to be cardioprotective during myocardial ischemia/reperfusion (IR), mechanism of BNP gene expression by IR has not been clarified yet. Here, we show the mechanism underlying IR‐induced BNP gene expression in H9c2 rat cardiomyocytes.IR induced expression of BNP mRNA and transactivation of BNP promoter in H9c2 cells. Activation of MAP kinase family members such as ERK1/2 and p38 MAPK was triggered by IR. U0126, an inhibitor of MEK, but not SB203580, an inhibitor of p38 MAPK, completely prevented increase of IR‐induced BNP gene expression. In addition, antioxidants such as DMSO and TEMPO diminished induction of BNP and phosphorylation of ERK1/2. To investigate whether increase in free intracellular calcium [Ca2+]i has a role in expression of BNP by IR, calcium chelator BAPTA‐AM was treated before reperfusion. BAPTA‐AM strongly reduced induction of BNP by IR. Moreover, calcium ionophore A23187 increased levels of BNP mRNA and phosphorylation of ERK1/2. Taken together, IR‐mediated BNP gene expression may be due to calcium‐ and ROS‐mediated activation of ERK1/2 in H9c2 cells. This research was supported by MRC from cell death disease research center funded by KOSEF.

Curcumin Reduces Angiotensin II-mediated Cardiomyocyte Growth via LOX-1 Inhibition

Curcumin, a natural polyphenolic compound, has been shown to reduce cardiomyocyte growth. Angiotensin II type 1 receptor (AT1R) and lectin-like oxidized low density lipoprotein (ox-LDL) receptor-1 (LOX-1) are major stimuli for cardiomyocyte growth via activation of oxidant signals. We postulated that curcumin may reduce Ang II-mediated cardiomyocyte growth via AT1R and LOX-1 inhibition. Adult mouse cardiomyocytes (HL-1) were incubated overnight in serum-free medium, and then treated with solvents or curcumin, the AT1R inhibitor losartan or anti-LOX-1 antibody for 3 hours, and the cells were then stimulated with Ang II. We measured cardiomyocyte growth, and associated intracellular redox signals using reverse transcriptase-polymerase chain reaction and quantitative real-time RT-PCR. We also examined the effect of curcumin on cardiomyocyte biology with forced overexpression of LOX-1 gene. Curcumin (5-10 microM), losartan, and anti-LOX-1 antibody markedly attenuated Ang II-mediated oxidant stress, and the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and nuclear factor-kappaB (NF-kappaB). Attenuation of redox state by curcumin resulted in abrogation of Ang II-mediated cardiomyocyte growth and atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) genes. Curcumin also reduced Ang II-mediated upregulation of AT1R and LOX-1. The forced upregulation of LOX-1 enhanced the expression of genes for AT1R, ANP, and BNP, and curcumin pretreatment reduced LOX-1 and AT1R expression and LOX-1-mediated increase in hypertrophy markers. Curcumin attenuates Ang II-mediated cardiomyocyte growth by inhibiting LOX-1 and AT1R expression and suppressing the heightened intracellular redox state.

Cardiac hormones ANF and BNP modulate proliferation in the unidirectional mixed lymphocyte reaction

Previous investigations have shown that the plasma levels of the cardiac hormone brain natriuretic peptide (BNP) increase during acute cardiac allograft rejection as diagnosed by endomyocardial biopsy. Successful immunosuppressant treatment decreased plasma BNP levels, suggesting a role for BNP in transplantation immunity. We tested a possible immunomodulatory effect of the natriuretic peptides (NPs) BNP, atrial natriuretic factor (ANF), and C-type NP (CNP) using the unidirectional mixed lymphocyte reaction (MLR). Lymphocytes were isolated from the lymph nodes of Brown Norway (BN) and Lewis (L) rats. BN lymphocytes were gamma-irradiated to inhibit DNA synthesis. Lymphocytes at 2.5 x 10(6) cell/ml were mixed (at an L:BN ratio of 4:1) and incubated. On Days 2 and 3, ANF (10(-6) to 10(-11) mol/liter), BNP (10(-5) to 10(-11) mol/liter), or CNP (10(-6) to 10(-12) mol/liter) were added. Cell proliferation was measured on Day 4. Reverse transcript-polymerase chain reaction (RT-PCR) analysis of BN and L lymphocytes detected NP receptor (NPR) mRNA amplicons of the expected size. MLR induced an increase in relative receptor abundance as follows: NPRA > NPRB > NPRC. ANF and BNP significantly inhibited up to approximately 50% lymphocyte proliferation in a dose-dependent manner in the range of 10(-11) to 10(-6) mol/liter, whereas CNP significantly decreased lymphocyte proliferation only modestly (approximately 20%) at 10(-8) mol/liter and at 10(-6) mol/liter. Both ANF and BNP have immunomodulatory functions, although the response to cardiac rejection observed clinically involves increases in plasma levels of BNP only. This is likely related to BNP gene promoter sequences previously reported to be responsive to specific cytokines and related substances. The modulation of the MLR by NP suggests a possible clinical use of these peptides in transplantation immunity.

The T-381C SNP in BNP gene may be modestly associated with type 2 diabetes: an updated meta-analysis in 49 279 subjects

A recent study reported an association between the brain natriuretic peptide (BNP) promoter T-381C polymorphism (rs198389) and protection against type 2 diabetes (T2D). As replication in several studies is mandatory to confirm genetic results, we analyzed the T-381C polymorphism in seven independent case-control cohorts and in 291 T2D-enriched pedigrees totalling 39 557 subjects of European origin. A meta-analysis of the seven case-control studies (n = 39 040) showed a nominal protective effect [odds ratio (OR) = 0.86 (0.79-0.94), P = 0.0006] of the CC genotype on T2D risk, consistent with the previous study. By combining all available data (n = 49 279), we further confirmed a modest contribution of the BNP T-381C polymorphism for protection against T2D [OR = 0.86 (0.80-0.92), P = 1.4 x 10(-5)]. Potential confounders such as gender, age, obesity status or family history were tested in 4335 T2D and 4179 normoglycemic subjects and they had no influence on T2D risk. This study provides further evidence of a modest contribution of the BNP T-381C polymorphism in protection against T2D and illustrates the difficulty of unambiguously proving modest-sized associations even with large sample sizes.

Abstract 4579: Endogenous Brain Natriuretic Peptide (BNP) Protects Against Apoptosis of Ischemic Human Astrocytes in an Autocrine Fashion

The plasma brain natriuretic peptide (BNP) level is increased in the acute phase of human stroke, but its source and function are unclear. Recently, we showed that the BNP level was higher in atherothrombotic cerebral infarction (69.1±9.4 pg/ml) than in control subjects (31.1±5.4 pg/ml), and that the BNP level in ischemic stroke was positively correlated with the NIH Stroke Scale (r=0.41, p&lt;0.05) and infarct volume (r=0.34, p&lt;0.05). Astrocytes provide metabolic and trophic support to neurons and modulate synaptic activities. At the early stage of brain ischemia, astrocytes are swollen, and their damage may compromise postischemic neuronal survival. We tested the hypothesis that human astrocytes produce BNP under hypoxia, and this endogenous BNP protects against apoptosis in an autocrine fashion. The human astrocyte cell line, U373MG, was exposed to hypoxia (O 2 ≤1%) for 24 hours. The ratio of BNP to GAPDH mRNA was increased by 7.7±.0 fold after 12-hour hypoxia and further increased by 8.6±1.6 fold after 24-hour hypoxia compared with that in 3-hour normoxia (both, p&lt;0.01). The protein expression assessed by Western blot was increased by 2.0±0.4 fold at 24 hours (n=5, p&lt;0.05). Tyrosine phosphorylation of c-Src was observed by 2.0±0.2-fold increase at 30 minutes. These responses to hypoxia were all blocked by pretreatment with PP1 at 50μM, an inhibitor of c-Src. Apoptosis was measured by detecting caspase activation by flow cytometry, and it was increased by 2.5±0.1 fold after 24-hour hypoxia compared with that in normoxia. To investigate the role of up-regulated BNP in apoptosis, we performed the loss of function test by transfecting a specific siRNA for NPPB that suppressed BNP by more than 80%. The activity of caspases in the BNP knockdown cells was increased by 3.2±0.2 fold after 24-hour hypoxia compared with that in normoxia (n=5, p&lt;0.001), and it was greater than that in the cells transfected with non-targeting siRNA. These results indicate that hypoxia increases BNP gene expression through the c-Src-dependent signaling cascade in the human astrocytes. Endogenous BNP shows brain protection via the anti-apoptotic effect. BNP may be useful in the treatment of ischemic brain diseases.

A novel alternative spliced variant of the brain natriuretic peptide gene is superior to BNP as a molecular marker of ventricular dysfunction

Background and Aim: Two mRNA isoforms of BNP (i.e., immature and mature transcripts) were found to be expressed in both normal and diseased porcine heart. Given that there were indications suggesting that heart failure (HF) may be associated with production of various isoforms of BNP, we searched for novel variants of alternative splicing of BNP in the porcine model of HF. Methods: HF was induced in 6-day-old neonatal piglets by a single i.v. injection of 2 mg/kg of Doxorubicin (Dox). To profile the cardiac gene expression changes associated with Dox-induced HF, a non-radioactive mRNA differential display (DDRT-PCR) was used. A novel alternative spliced variant of the BNP gene (designated E2-BNP) was identified, characterized, cloned and expressed. E2-BNP mRNA levels were determined by semi-quantitative and qRT-PCR. Results: On day 24 after Dox-administration, experimented piglets developed the features of diastolic HF. Using DDRT-PCR, the band corresponding to the E2-BNP was identified as being overexpressed in failing versus normal piglet myocardium. The sequence of this band displayed a 100% homology with exon 1 and exon 3 sequences of BNP. Further RT-PCR amplification of BNP (through exons 1-3) from the failing piglet myocardium cDNA produced three products, two of which were identical to the reported BNP immature and mature transcripts, whereas the third one was characterized by the precise deletion of the exon 2. Skipping of exon 2 ( E2) causes a frame-shift from the beginning of exon 3, generating a coding sequence for a new protein with no C-terminal homology to known natriuretic peptides. In newborn piglets (n=5), the E2-BNP mRNA was 15 fold more abundant in the left ventricle (LV) than in the right ventricle (RV). During development, the E2-BNP gene expression is rapidly downregulated in both ventricles being, at postnatal day 30, 10-20-fold lower as compared to newborn piglets. By contrast, in 30-day-old piglets with Dox-induced HF (n=12) the E2-BNP mRNA levels were found to be consistently and significantly augmented in both ventricles being much more up-regulated in the RV (40±2.6 fold) than in the LV (10±1.6 fold) as compared with age-matched controls. The average fold-increase of the BNP mRNA content in the failing porcine RV and LV was only 6.3±0.5 and 5.1±0.3, respectively. Conclusion: As such, variation in E2-BNP mRNA transcript abundance within the ventricular wall can be used to diagnose heart conditions in large-animal models of HF. In addition, the E2-BNP seems to be superior to BNP as a molecular marker for HF.

Disease-Modifying Mutations in Familial Hypertrophic Cardiomyopathy

Cardiomyopathies are primary disorders of cardiac muscle associated with abnormalities of cardiac wall thickness, chamber size, contraction, relaxation, conduction, and rhythm. They are a major cause of morbidity and mortality at all ages and, like acquired forms of cardiovascular disease, frequently progress into heart failure.1 In contrast to dilated cardiomyopathy (DCM), which is characterized by left or biventricular dilation in association with depressed myocardial contractility,1 familial hypertrophic cardiomyopathy (FHC) is characterized by increased cardiac mass with myocyte and myofibrillar disarray. The disease is associated with electrical instability (ie, atrial and ventricular arrhythmias), which makes it the leading cause of death in young athletes. There is marked diversity in the morphological features and clinical manifestations of both DCM and FHC.2 Article p 1820 Family studies have demonstrated that hypertrophic cardiomyopathy is a heritable disorder that is transmitted as an autosomal-dominant trait or as a sporadic disease. There is neither a racial nor an ethnic predisposition to this condition. Hypertrophic cardiomyopathy is not a rare condition; several noninvasive studies have demonstrated echocardiographic criteria for this disease in 0.2% of young adults (reviewed by Maron3). Genetic linkage studies in FHC have found disease loci on at least 14 different genes, most of them encoding sarcomeric genes; hence, FHC has been called a disease of the sarcomere. In addition, several mutations within the Ras pathway have been shown to cause at least syndromic forms of hypertrophic cardiomyopathy,4,5 pointing to the presence of additional but poorly understood disease-causing and/or modifier genes. Thus far, however, most of the clinical heterogeneity of FHC has been accounted for by the substantial diversity of gene defects that cause the condition (ie, up to 45% of disease-causing mutations have been observed in the β-myosin heavy chain [MHC] gene myh7 and up to 35% in …

Chronic Contamination of Rats with 137Cesium Radionuclide: Impact on the Cardiovascular System

Cardiovascular system impairment has been observed in children and in liquidators exposed to the Chernobyl nuclear power plant accident. No experimental studies of animals have analyzed whether these disorders might be attributed to chronic ingestion of low levels of cesium 137 ((137)Cs). Biochemical, physiological, and molecular markers of the cardiovascular system were analyzed in rats exposed through drinking water to (137)Cs at a dose of 500 Bq kg(-1) (6500 Bq l(-1)). Plasma concentrations of CK and CK-MB were higher (+52%, P < 0.05) in contaminated rats. No histological alteration of the heart was observed, but gene expression was modified in the atria. Specifically, levels of ACE (angiotensin converting enzyme) and BNP (brain natriuretic peptide) gene expression increased significantly (P < 0.05). ECG analysis did not disclose any arrhythmia except ST- and RT-segment shortening (-9% and -11%, respectively, P < 0.05) in rats exposed to (137)Cs. Mean blood pressure decreased (-10%, P < 0.05), and its circadian rhythm disappeared. Overall, chronic contamination by an extreme environmental dose of (137)Cs for 3 months did not result in cardiac morphological changes, but the cardiovascular system impairments we observed could develop into more significant changes in sensitive animals or after longer contamination.

Relationship Between Natriuretic Peptides and Inflammation: Proteomic Evidence Obtained During Acute Cellular Cardiac Allograft Rejection in Humans

Cardiac natriuretic peptides (NPs) atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) are polypeptide hormones secreted by the heart. Previously, we found that BNP, but not ANF, plasma levels may increase during an acute cellular cardiac allograft rejection episode. In vitro, the pro-inflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) produced a selective increase of BNP gene expression and secretion. Other pro-inflammatory cytokines had no such effects. We identified cytokines associated with the selective upregulation of BNP during cardiac allograft rejection using a proteomics approach to measure 120 cytokines and related substances in the plasma of 16 transplant patients before, during and after an acute rejection episode. The values obtained were correlated with BNP plasma levels. Cytokines identified as being significantly related to BNP plasma levels were tested in neonatal rat ventricular cardiocytes in culture for their ability to selectively promote BNP secretion. The signaling pathway related to this phenomenon was pharmacologically characterized. Regulated-on-activation, normal T-expressed and secreted (RANTES), neutrophil-activating protein-2 (NAP-2) and insulin growth factor binding protein-1 (IGFBP-1) had significant correlations with BNP plasma levels during Grade 3A (Grade 2 revised [2R]) or above rejection as diagnosed by endomyocardial biopsy score according to the International Society for Heart and Lung Transplantation (ISHLT) grading system. In rat neonatal ventricular cardiocyte cultures, IGFBP-1 and RANTES were capable of promoting BNP, but not ANF secretion, as observed in rejecting patients. The BNP-promoting secretion activity of the identified cytokines was abolished by SB203580, a specific p38 MAP kinase inhibitor. This work shows that cytokines other than pro-inflammatory cytokines correlate with BNP plasma levels observed during acute cardiac allograft rejection, and that the substances identified have in common p38 signaling. This finding provides a unifying mechanistic explanation regarding the relationship between inflammation and cardiac hormone production in acute cardiac allograft rejection.

Extracellular Calcium Alters Contractile Force but Not Gene Expression of BNP, SERCA, or NCX in Isometrically Contracting Human Myocardium

Introduction: The expression of genes that code for proteins involved in cellular calcium handling, such as sarco-endoplasmatic reticulum calcium ATPase (SERCA) and Na+-Ca2+ exchanger (NCX), as well as the expression of the brain natriuretic peptide (BNP) gene, is altered in a characteristic fashion in congestive heart failure. Several of the respective molecular pathways involve cytoplasmic calcium. Hypothesis: We hypothesized that contractile force and synthesis of these proteins depend on the extracellular calcium concentration in isometrically contracting human myocardium.

Effects of daunorubicin on the expression of brain natriuretic peptide gene in myocardial cells: an in vitro experiment with cultured myocardial cells from rats

To investigate the effects of daunorubicin (DNR) on the gene expression of brain natriuretic peptide (BNP) in myocardial cells. Myocardial cells were isolated from neonatal Wistar rats, cultured, and added with DNR of the concentrations of 0, 0.02, 0.2, and 2 mg/L respectively so as to calculate the maximum non-toxic concentration of DNR. The cultured rat myocardial cells were divided into 3 groups, DNR group, added with DNR 0.2 mg/L, DNR+fructose-1, 6-diphosphate (FDP) group, added with DNR 0.2 mg/L and FDP 2 mg/ml, and control group. The viability of the myocardial cells was examined by MTT method. RT-PCR and Western blotting were used to detect the mRNA expression and protein expression of the BNP gene. Toxicity test showed that the maximum non-toxic concentration of DNR was 0.2 mg/L. Western blotting showed that the average grey level ratio of BNP/GAPDH of the DNR group was 0.40+/-0.09, not significantly different from that of the DNR+FDP group (0.42+/-0.11, but significantly lower than that of the control group (0.82+/-0.13, P<0.01). DNR suppresses the expression of BNP gene in myocardial cells and FDP cannot reverse the suppressing effect.

Association between the T-381C polymorphism of the brain natriuretic peptide gene and risk of type 2 diabetes in human populations

Brain natriuretic peptide (BNP/NPPB) is a member of the natriuretic family involved in the regulation of blood pressure and blood volume as well as lipolysis control in human fat cells. Thus BNP may play a role in energy metabolism and metabolic diseases. We therefore assessed the association between the BNP promoter T-381C polymorphism and risk of type 2 diabetes and metabolic and BNP expression traits in several population samples. In French population-based samples (n = 3216), we found that individuals bearing the -381CC genotype had lower (P = 0.005) fasting glucose levels than -381TC or -381TT individuals. Moreover, the -381CC genotype was less frequent in individuals with type 2 diabetes (n = 280, 13.6%) or with impaired fasting glucose (n = 248, 12.9%) compared with normoglycaemic individuals (n = 2485, 17.8%). The adjusted odds ratio (OR) (95% CI) of type 2 diabetes for -381CC individuals was 0.69 (0.47-1.00), P = 0.05, when compared with -381T allele bearers. We replicated this association in four additional case-control studies for type 2 diabetes. The overall OR (95% CI) of type 2 diabetes was 0.85 (0.76-0.96), P = 0.008, (under a recessive model) (3593 cases and 6646 controls in total). We also found that the -381C allele was associated with higher plasma BNP concentrations (P = 0.015, n = 634) and higher BNP promoter activity in reporter gene assays. Collectively, these data suggest that relatively high BNP expression may protect against type 2 diabetes in humans.

Determinants of brain natriuretic peptide gene expression and secretion in acute cardiac allograft rejection

Circulating levels of the cardiac hormone brain natriuretic peptide in heart transplant patients may increase before and during an acute rejection episode. A similar increase in atrial natriuretic factor does not occur. This article reviews the possible significance of these findings. During acute cardiac allograft rejection episodes, brain natriuretic peptide plasma levels may increase well above baseline values. This increase is not the result of hemodynamic changes because brain natriuretic peptide levels during International Society for Heart and Lung Transplantation grade 3 rejection do not correlate with various hemodynamic parameters, and atrial natriuretic factor levels are not affected. Similar results were observed in experimentally induced autoimmune myocarditis. In-vitro data showed that some proinflammatory cytokines and chemokines are capable of selectively increasing brain natriuretic peptide gene expression and secretion in cardiocyte cultures. Atrial natriuretic factor and brain natriuretic peptide are usually co-regulated. Findings in heart allograft recipients, in experimentally induced myocarditis, and in vitro suggest that, unlike atrial natriuretic factor, brain natriuretic peptide is uniquely related to inflammation. These findings may translate into biomarkers or therapies for cardiac allograft rejection or myocarditis and may explain the existence of two hormones with nearly identical biologic properties.

A Novel Variable Number of Tandem Repeat of the Natriuretic Peptide Precursor B gene's 5'-Flanking Region is Associated with Essential Hypertension among Japanese Females

Brain natriuretic peptide (BNP) acts primarily as a cardiac hormone; it is produced by the ventricle and has both vasodilatory and natriuretic actions. Therefore, the BNP gene is thought to be a candidate gene for essential hypertension (EH). The present study identified variants in the 5'-flanking region of natriuretic peptide precursor B (NPPB) gene and assessed the relationship between gene variants and EH. The polymerase chain reaction-single strand conformation polymorphism method and nucleotide sequencing were used to identify variants. A novel variable number of tandem repeat (VNTR) polymorphism in the 5'-flanking region (-1241 nucleotides from the major transcriptional initiation site) was discovered. This VNTR polymorphism is a tandem repeat of the 4-nucleotide sequence TTTC. There were 8 alleles, ranging from 9-repeat to 19-repeat. An association study was done involving 317 EH patients and 262 age-matched normotensive (NT) subjects. The 11-repeat allele was the most frequent (88.2%); the 16-repeat allele was the second most frequent (10.5%) in the NT group. The observed and expected genotypes were in agreement with the predicted Hardy-Weinberg equilibrium values (P=0.972). Among females, the overall distribution of genotypes was significantly different between the EH and NT groups (p=0.039). The frequency of the 16-repeat allele was significantly lower in the female EH group (6.5%) than in the female NT group (12.2%, p=0.046). The 16-repeat allele of the VNTR in the 5'-flanking region of NPPB appears to be a useful genetic marker of EH in females.